1. Field of Invention
The present invention belongs to a permanent magnetic material field, and more particularly to a method for producing a high-performance neodymium-iron-boron rare earth permanent magnetic material.
2. Description of Related Arts
Due to the excellent magnetic properties, the neodymium-iron-boron rare earth permanent magnetic material is getting more and more applications and has been widely used in the medical magnetic resonance imaging, the computer hard disk drive, the sound, the mobile phone and so on. With the energy-saving and low-carbon economy requirements, the neodymium-iron-boron rare earth permanent magnetic material began to be applied in the auto parts, the household appliances, the energy-saving and control motors, the hybrid electric vehicles, the wind power and other fields.
In 1982, Japan Sumitomo Special Metals Company firstly disclosed the Japanese patent Nos. 1,622,492 and 2,137,496 about the neodymium-iron-boron rare earth permanent magnetic material, and then the U.S. patent and European patent are applied, which disclosed the characteristics, components and manufacturing method of the neodymium-iron-boron rare earth permanent material, and confirmed the main phase: Nd2Fe14B phase, the grain boundary phase: Nd-rich phase, B-rich phase and the rare earth oxide impurities.
On Apr. 1, 2007, Japan Hitachi Metals Company was merged with Japan Sumitomo Special Metals Company, and inherited the patent license right and obligation about the neodymium-iron-boron rare earth permanent magnet of the Sumitomo Special Metals Company. On Aug. 17, 2012, the Hitachi Metals Company brought a lawsuit to the U.S. International Trade Commission (ITC) that it had the patent right of U.S. Pat. No. 6,461,565, U.S. Pat. No. 6,491,765, U.S. Pat. No. 6,537,385 and U.S. Pat. No. 6,527,874.
The filing date of the U.S. Pat. No. 6,461,565 is May 8, 2001, the corresponding Chinese patent application number is CN1195600C, this patent believes that it is difficult to have the magnetic compaction under the protective atmosphere, this application claimed the magnetic compaction under the atmosphere, the working temperature is larger than 5° C. and smaller than 30° C., and the relative humidity is between 40% and 65%. The powder is compacted under this environment.
U.S. Pat. No. 6,491,765 filed on May 9, 2001 and U.S. Pat. No. 6,537,385 filed on Jul. 9, 2001 filed a Chinese patent No. CN1272809C, this patent claimed that the powder is prepared by the inert gas jet mill with the oxygen content is 0.02-5%, at least a part of ultra-fine powders with the particle size of less than 1 μm are removed by the cyclone collector, thus the total amount of the ultra-fine powders with the particle size of less than 1 μm in the powder is controlled to less than 10%. The jet mill uses the cyclone collector to collect the powder, so a part of the particles with the size of less than 1 μm discharged along the airflow is the natural process.
Japan Hitachi Metals Company filed a U.S. Pat. No. 6,537,874 on Jul. 10, 2001, and a Chinese Patent No. CN1182548C claimed a strip casting technology of a neodymium-iron-boron rare earth permanent magnetic alloy melting process at least containing the metal element Nb or Mo.